News and Articles on Target Earth

2009 July 21. NASA
images show Jupiter apparently hit by object. Pasadena,
Calif. (AP) -- Astronomers say Jupiter has
apparently been struck by an object, possibly
a comet. Images taken by NASA early Monday
show a scar in the atmosphere near the south
pole of the gas giant. The images, taken
by the space agency's infrared telescope
in Hawaii, come on the 15th anniversary of
another comet strike. In 1994, Jupiter was
bombarded by pieces of the comet Shoemaker-Levy
9. Scientists at NASA's Jet Propulsion Laboratory
in Pasadena captured the new images after
receiving a tip from an amateur astronomer
the night before. See also:Amateur
Finds New Earth-Sized Blot on Jupiter -
NASA has confirmed the discovery of a new "scar" the
size of the Earth in Jupiter's atmosphere,
apparently showing that the planet was hit
by something large in recent days.NASA
RELEASE: 09-176. Hubble
Space Telescope Captures Rare Jupiter
Collision.
- NASA's Hubble Space Telescope has taken the
sharpest visible-light picture yet of atmospheric
debris from an object that collided with Jupiter
on July 19.

2009 April 28. New
Blow Against Dinosaur-killing Asteroid Theory,
Geologists Find. NSF Press Release. The
enduringly popular theory that the Chicxulub
crater holds the clue to the demise of the
dinosaurs, along with some 65 percent of
all species 65 million years ago, is challenged
in a paper to be published in the /Journal
of the Geological Society on April 27, 2009.

2009 Mar 25. First-Ever
Asteroid Tracked From Space to Earth. By Betsy Mason. For the
first time, scientists were able to track an
asteroid from space to the ground and recover
pieces of it. The bits are unlike anything
ever found on Earth. The asteroid was spotted
entering Earth's atmosphere over Sudan in October
and was believed to have fully disintegrated,
but an international team found almost 280
pieces of meteorite in a 11-square-mile section
of Sudan's Nubian Desert.

September 17, 2007. Melted
Crumbs from Asteroid Vesta. By Linda
M. V. Martel, Hawai'i Institute of Geophysics
and Planetology. Excerpt: Researchers studying
some of the rarest of the smallest meteorites
call them melted crumbs from asteroid Vesta.
Micrometeorite bombardment accounts for almost
30,000 tons of material entering Earth's
atmosphere each year. Though most of the
material evaporates during entry or is lost
to sea or falls on the land unnoticed, thousands
of micrometeorites have been collected successfully
from deep-sea sediments and from the snow
and ice of the polar caps. Susan Taylor (Cold
Regions Research and Engineering Laboratory)
and colleagues collected micrometeorites
with an ingeniously designed robot from a
decidedly out-of-the-way place: Amundsen-Scott
South Pole Station water well. She and Greg
Herzog and Jeremy Delaney (Rutgers University)
selected 10 out of thousands of these extraterrestrial
particles, 75 to 700 micrometers in size,
because of their unusual shapes and mineralogy,
and measured the Fe/Mn and Fe/Mg elemental
ratios, which are known to help constrain
the type and source of meteorites. The results
show that nine of the cosmic spherules are
broadly chondritic in composition as expected.
However, one, along with six others reexamined
from a previous study, are atypical with
nonchondritic compositions. Taylor and coauthors
propose an origin from an achondrite, Howardite-Eucrite-Diogenite
(HED)-like parent body such as asteroid Vesta.
HED-like objects account for about 6% of
all meteorites, and only about 0.5% of all
micrometeorites perhaps because of a natural
mechanical toughness that would resist breakup
and fragmentation....

January 3, 2007. Metal
object crashes through N.J. home. By
CHRIS NEWMARKER, Associated Press Writer
Excerpt: FREEHOLD TOWNSHIP, N.J. - A metal,
rock-like object about the size of a golf
ball and weighing nearly as much as a can
of soup crashed through the roof of a Monmouth
County home, and authorities on Wednesday
were trying to figure out what it was. ...Police
received a call Wednesday morning that the
metal object had punched a hole in the roof
of a single-family, two-story home, damaged
tiles on a bathroom floor below and then
bounced, sticking into a wall. ...Brightman
said one man who lives at the home found
the object at about 9 p.m. Tuesday after
returning from work and hearing from his
mother that something had crashed through
the roof a few hours before....Approximately
20 to 50 rock-like objects fall every day
over the entire planet, said Carlton Pryor,
a professor of astronomy at Rutgers University. "It's
not all that uncommon to have rocks rain
down from heaven," ...Pryor said laboratory
tests would have to be conducted to determine
if the object were a meteorite.

April
20, 2005. NASA's
Spitzer Telescope Sees Signs of Alien Asteroid Belt.
Spitzer Press Release. NASA's Spitzer Space
Telescope has spotted what may be the dusty
spray of asteroids banging together in a
belt that orbits a star like our Sun. The
discovery offers astronomers a rare glimpse
at a distant star system that resembles our
home, and may represent a significant step
toward learning if and where other Earths
form. ... Dr. Charles Beichman of the California
Institute of Technology, Pasadena, Calif... "We can't directly
see other terrestrial planets, but now we can study their dusty
fossils." Asteroid belts are the junkyards of planetary
systems. They are littered with the rocky scraps of failed planets,
which occasionally crash into each other, kicking up plumes
of dust. In our own solar system, asteroids have collided with
Earth, the moon and other planets. If confirmed, the new asteroid
belt would be the first detected around a star about the same
age and size as our Sun. The star, called HD69830, is located
41 light-years away from Earth. There are two other known distant
asteroid belts, but they circle younger, more massive stars.
...Beichman and colleagues used Spitzer's infrared spectrograph
to observe 85 Sun-like stars. Only HD 69830 was found to possibly
host an asteroid belt. They did not see the asteroids themselves,
but detected a thick disk of warm dust confined to the inner
portion of the star system. The dust most likely came from an
asteroid belt in which dusty smash-ups occur relatively frequently,
about every 1,000 years. "Because this belt has more asteroids
than ours, collisions are larger and more frequent, which is
why Spitzer could detect the belt," said Dr. George Rieke,
University of Arizona, Tucson, co-author of the paper. "Our
present-day solar system is a quieter place, with impacts of
the scale that killed the dinosaurs occurring only every 100
million years or so."....

Feb 2005.
The Sloan Digital Sky Survey. By Michael A.
Strauss and Gillian R. Knapp. Sky & Telescope magazine.
This is a fascinating article with sections
on "The Origins
of Asteroid Families", "Neither Stars nor Planets",
"Cannibalism and the Milky Way", "Cosmological
Mirages." Lots of interesting techniques for using filters.
Excerpt (in the asteroid section): Mounted at the survey telescope's
focal plane, the SDSS imaging camera simultaneously scans the
sky through five rows of color filters: u (for ultraviolet),
g (for green), r (for red), i (infrared), and z (a longer wavelength
infrared band). Well not exactly simultaneously; the five are
observed sequentially (r, i, u, z, and g), with roughly a five
minute of time separating each. In the five minutes between
the r and g exposures of a given patch of sky, Earth advances
9,000 km along its orbit, creating a parallax of several arcseconds
in the apparent position of a main-belt asteroid (the effect
of the asteroid's own orbital motion is several times smaller).
...The SDSS software recognizes this characteristic motion and
can thus distinguish asteroids from much more numerous images
of stars. The SDSS has precisely measured the colores of some
100,000 asteroids to date -- more than 100 times the number
for which colors had been available beforehand.... An asteroid's
orbit around the Sun is characterized by three numbers: its
semimajor axis, its eccentricity; and its inclination. Plotting
these quantities for all known asteroids shows clumps with similar
orbits, termed "families." It has long been suggested
that the members of a particular family are shards of a larger
single body that was broken up in a collision some time ago.
If this were the case, one would expect that a given family's
asteroids would share the same composition and age and therefore
would have similar colors. The SDSS data confirm this hypothesis
dramatically. Collisions aren't the only processes that alter
asteroids. Planetary scientists have predicted that asteroid
colors should evolve as the rocky objects' surfaces are altered
by the solar wind and by micrometeoroid impacts. The Sloan asteroids'
colors and orbital parameters support this "space weathering"
hypothesis (S&T: October 2004, page 26).
They also solve a long-standing mystery: why
the interiors of meteorites that have fallen
to Earth have colors that differ from those
of the commonest asteroids. [SDSS website is http://www.sdss.org/]

Dec. 2002
Did a Comet Swarm Kill the Dinosaurs? by
DAVID TYTELL, Sky & Telescope magazine, p. 24. IN 1991
A MODERN SCIENTIFIC "WHODUNIT" WAS
SOLVED WHEN geologists identified a deeply
buried, 180-kilometer-Wide crater in the Yucatan
peninsula. Now known as Chicxulub, the scar
resulted from the impact of a 10-km asteroid
or comet nucleus 65 million years ago. Geologic
evidence indicates that the impact triggered
global tidal waves, worldwide firestorms, and
massive earthquakes. It also left a worldwide
layer of extraterrestrial dust. When Earth
finally returned to normal, the dinosaurs and
the majority of all then-living species had
gone extinct, opening the way for mammals to
diversify and dominate Earth.

Height
of meteors measured: "…pinpoint
glow occurred at an altitude of 115 kilometers.
Only 300 milliseconds later, at 107 km, the
tiny meteoroid had developed a luminous bow
shock about 600 meters (2,000 feet) wide."

September
3, 2003. Make a note: 21 March 2014 might just be Asteroid D-day.
By Charles Arthur, Technology Editor of http://www.independent.co.uk -- "The
Earth is imperilled by an asteroid again, which
will strike the planet on 21 March 2014 if
our luck turns out to be truly bad, astronomers
say."

July 21,
2003 Search for Large Asteroids Nears Completion, Experts Ponder
Gaps in Program, By Michael Paine. SYDNEY, Australia -- A stated
goal of finding 90 percent of all large Near Earth Asteroids
(NEAs) by 2008 is more or less on target, .... The goal, originally
outlined by NASA and mandated by the U.S. Congress, is designed
to insure that space rocks in the vicinity of Earth's orbit,
and larger than 1 kilometer (0.62 miles), are found and tracked.
An object of this size could cause global destruction if one
were to hit Earth. .... The global experts gathered here reiterated
a common concern among asteroid scientists: When the current
goal is reached, there will still be many unfound smaller objects
that are easily capable of destroying a large city. Full
story.

06/11/2003
Evidence for meteor in early mass extinction
found ... LSU geophysicist Brooks Ellwood
is plumbing the geologic record, trying to
correlate known mass extinctions to meteor
strikes.... Ellwood and four other researchers
have just published an article in the journal
Science in which they tie an early mass extinction
to a meteor strike. This extinction happened
380 million years ago in what is called the
middle Devonian. It was a time when only
small plants, wingless insects and spiders
inhabited the land and everything else lived
in the sea. About 40 percent of all species
disappeared from the fossil record at this
time. The extinction
has been known to geologists for a long time
but this is the first time it has been tied
to a meteor strike. This is also the oldest
known impact that has been tied to a mass
extinction.... What is unique about Ellwood's
work, however, is the means he uses to identify
the different layers in the geologic record:
induced magnetism.... "The magnetic pattern
associated with an impact layer is often
distinctive, making it easier to find in
a thick sequence of strata," he said...."We
know that meteors have struck the Earth
hundreds of times," Ellwood said.
"If I had to guess, I would say that once every
5 million years a meteor big enough to cause
a mass extinction hits the Earth. See full
article.

March
26, 2003 ESA Press Release 19-2003:ESA
Studies Missions to Safeguard the Earth. http://www.esa.int/export/esaCP/Pr_19_2003_p_EN.html.
The six missions under study were: Don
Quijote: This
proposal involves the launch of two spacecraft
to test technologies required to deflect
an asteroid heading towards Earth. Earthguard
1: A proposal to mount a "hitchhiker"
telescope on a spacecraft en route to the
inner Solar System,... EUNEOS: A
medium-sized telescope mounted on a dedicated
spacecraft platform that would search for
the most dangerous NEOs from inside the
orbit of Venus. ISHTAR:
In addition to measuring the mass, density
and surface properties of an NEO, this spacecraft
would probe the interior of an NEO in order
to study its structure and internal strength. SIMONE:
A fleet of five low-cost microsatellites that
would each fly by and/or rendezvous with a
different type of NEO. Remote observation
of NEOs from Space: A space-based
observatory to carry out remote sensing and
detect physical characteristics of NEOs, such
as size, composition and surface properties.

March
17, 2003 -- WORRIED ABOUT ASTEROID-OCEAN IMPACTS? DON'T SWEAT
THE SMALL STUFF. From Lori Stiles, UA News Services, 520-621-1877.
The idea that even small asteroids can create hazardous tsunamis
may at last be pretty well washed up. Small asteroids do not
make great ocean waves that will devastate coastal areas for
miles inland, according to both a recently released 1968 U.S.
Naval Research report on explosion-generated tsunamis and terrestrial
evidence. Full Article

March
6, 2003. NASA's Newest Maps Reveal a Continent's Grandeur
and a Secret. The existence of the
impact crater known as Chicxulub (Chik-sah-loob)
was first proposed in 1980. In the 1990s, satellite
data and ground studies allowed it to gain
prominence among many scientists as the long
sought-after "smoking
gun" responsible for the demise of the dinosaurs
and more than 70 percent of Earth's living
species 65 million years ago. Now, the Shuttle
Radar Topography Mission has provided the most
telling visible evidence to date of a 180-kilometer
(112-mile) wide, 900-meter (3,000-foot) deep
impact crater, the result of a collision with
a giant comet or asteroid on one of Earth's
all-time worst days. Full article at http://www.jpl.nasa.gov/releases/2003/30.cfm

January
2, 2003, Earth and Asteroid Play Orbital Cat and Mouse
Game--http://www.jpl.nasa.gov/releases/2003/1.cfm--The
first asteroid discovered to orbit the Sun in nearly the same
path as Earth will make its closest approach to our planet this
month before scurrying away for 95 years. The space rock, measuring
about 60 meters (approximately 200 feet) across, is like a mouse
teasing a cat. The asteroid approaches the Earth, first on one
side and then on the other. Animation: http://neo.jpl.nasa.gov/2002aa29.html

25 July
2002 (AP) Astronomers: Asteroid Hit Unlikely

By Andrew
Bridges -- http://www.space.com/spacewatch/asteroid_threat_020725.html
-- Astronomers said Wednesday that they are keeping close watch
on a newly discovered 1.2 mile-wide asteroid (2002 NT7) to determine
whether it will collide with Earth Feb. 1, 2019.

June 20,
2002. Paris (AFP) See Asteroid
Gives Earth Closest Shave In Years -- A football-pitch-sized
asteroid capable of razing a major city came within a whisker
of hitting the Earth on June 14, but was only spotted three
days later, ....

March
21, 2002, Close-call Asteroid Causes More Worries
By Stuart J. Goldman -- http://SkyandTelescope.com/news/current/article_545_1.asp
Excerpt: Billed as the "blind-spot" asteroid, a building-size
space rock passed the Earth unnoticed two weeks ago. An automated
sky survey detected minor planet 2002 EM7 on March 12th. Subsequent
orbital calculations determined that the asteroid had come closest
to the Earth four days earlier at a distance of about 464,000
kilometers (288,000 miles), slightly more than the distance
from the Earth to the Moon. Prior to the flyby, 2002 EM7 was
too close to the Sun, hence the "blind-spot" moniker.

Jan
28, 2002, The Great Dying--http://science.nasa.gov/headlines/y2002/28jan_extinction.htm?list617264
-- Excerpt: Somehow, most of the life
on Earth perished in a brief moment of geologic
time roughly 250 million years ago. Scientists
call it the Permian-Triassic extinction or "the
Great Dying" -- not to be confused with the
better-known Cretaceous-Tertiary extinction
that signaled the end of the dinosaurs 65 million
years ago. Whatever happened during the Permian-Triassic
period was much worse: No class of life was
spared from the devastation. Trees, plants,
lizards, proto-mammals, insects, fish, mollusks,
and microbes -- all were nearly wiped out.
Roughly 9 in 10 marine species and 7 in 10
land species vanished. Life on our planet almost
came to an end. Science@NASA.

December
17, 2001 -- Earth May Have Had Several Generations Of
Life Evolution -- http://www.cosmiverse.com/space12170103.html
-- Earth may have survived several early impacts from large
asteroids, causing life to disappear and reappear several times
according to a theory put forth recently. The early Earth, in
other words, may have been an interrupted Eden - a planet where
life repeatedly evolved and diversified, only to be sent back
to square one by asteroids 10 or 20 times wider than the one
that hastened the dinosaurs' demise. When the surface of the
Earth finally became inhabitable again, thousands of years after
each asteroid impact, the survivors would have emerged from
their hiding places and spread across the planet - until another
asteroid struck and the whole cycle was repeated. [Cosmiverse.]

Sunlight
Could Push Asteroids into Killer Orbits--Scientists have long
been puzzled about why there are asteroids in orbits outside
of the belt between Mars and Jupiter, but a new culprit might
have been uncovered: sunlight. U.S.-Czech research indicates
that the gradual force from sunlight could slowly push asteroids
into gravitational interaction with Jupiter, which could then
swing them into wild orbits, including those which cross the
Earth's orbit. For more information, go to http://www.swri.org/9what/releases/asteroid.htm

Nov 2001
Leonids Put on a Spectacular Show--It was one of the
most anticipated meteor showers in recent years, and to the
delight of skywatchers around the world, the Leonid Meteor Storm
of 2001 was a night to remember. Viewers in North America saw
up to 2,600 meteors an hour during perfect viewing conditions,
making it the best storm since 1966 (when skywatchers saw more
than 150,000 meteors an hour). Even though the peak of the storm
is over, you can expect to continue seeing Leonid meteors until
November 21st, when the Earth leaves the dust clouds left by
Comet Tempel-Tuttle. For more information, go to http://spaceweather.com/meteors/gallery_18nov01.html

Nov 7,
2001 Fewer Earth Crossing Asteroids Than Previously Thought--Some
good news: the Earth is less likely to be struck by an asteroid
than scientists previously calculated. The odds are only 1 in
5,000 that an asteroid big enough to wipe out civilization will
hit the Earth within the next 100 years (much lower than the
1 in 1,500 of earlier estimates). Astronomers from Princeton
University used data from the Sloan Digital Sky Survey to calculate
that there are 700,000 asteroids in the solar system larger
than 1 kilometre; but only a fraction of those will ever cross
the Earth's orbit. For more information, go to http://www.sdss.org/news/releases/20011108.asteroid.html

March
10, 2000 The
Ups and Downs of Impacts -- A team of scientists led
by Timothy S. Culler (University of California, Berkeley) concludes
that the rate of impacts on the Moon -- and therefore Earth
-- has taken some dramatic downs and ups over the past 4 billion
years.

March
14 Tagish Lake: Mystery Meteorite At
last year's Lunar and Planetary Science Conference,
held each March in Houston, Texas, meteorite
specialists were salivating over the Tagish
Lake meteorite, which had dropped as a hail
of fragments onto the Yukon's winter wilderness
just two months before. A year later, the Tagish
Lake fall is still causing a scientific buzz
because its unique composition, forged at the
very beginning of the solar system, defies
easy explanation.
"We were hoping to find all these amino acids," laments Iain
Gilmour (Open University), "and they're just not there." What
Gilmour and others have identified are puzzling
clues to the meteorite's origin. (Sky & Telescope magazine online)

December
18, 2000 Impact
crater examined for clues to dinosaurs' demise -- The
rock and dust kicked up by an asteroid impact 65 million years
ago were not enough to kill the dinosaurs, according to researchers
-- but the debris may have sparked a deadly global chemical
reaction in the atmosphere.

January
22, 1997-- Very early on the morning of January
22, 1997, Lottie Williams, a resident of
Tulsa, Oklahoma, was walking for exercise
in a park near her home. She saw a "big bright light, like
a fire" in the sky. "It was coming over the park and
as it approached us it got bigger. All the colors that you see
that come from fire, all those colors were there." A
few minutes later, Williams felt a gentle tap
on her shoulder. On the ground, she found a
light piece of charred metal, about the size
of her hand. After some investigation, Williams
confirmed that the metal fragment came from
a rocket that had been used to put a satellite
into orbit for the U.S. Air Force in 1996.
After nine months in space, a fuel tank from
the rocket crashed into an empty field in Texas.
A metal splinter from that tank hit Williams
on the shoulder... See full article on January
22, 2002: The
Center for the Study of Technology and Society. See also
The Aerospace Corporation.

... about half of the genera (plural of genus), animal and plant, died off.
... the asteroid was about 10 km across, moving 30 km/sec, while the oceans are at most about 5 km deep. The explosion released energy equivalent to 100 million megatons of TNT, more than 10,000 times the yield of all the nuclear weapons of the Cold War. Nearby rock would have been heated to ~20,000 K--a few times the surface temp. of the Sun! This would have been enough to vaporize the rock, but not enough to initiate fusion (someone asked him about this). Walter had several of the same slides that we use in our show. In particular he had a map of the USA and Mexico with some blue and red dots on it. The blue dots mark spots where the K-T boundary layer has been found; also there was a spot on the Brazos River (I think in Texas) where sandstones were found that were interpreted by Jody Bourgeious as tsunami deposits. The tsunami generated by the impact would have been about 1 km high. Current thinking is that the ash and dust and whatnot would have darkened the sky for only a few months--still enough to kill lots of plants and animals, but not a year or more, as the old script says. Also, the material thrown up would have generated 3 kinds of acid rain; Walter seemed to be saying that the acid rain would have been more important in killing things off than the lack of sunlight.

Finally, an exciting recent find is that geologists have found outcrops of the ejecta blanket in Belize.

Small Telescope Science Program's Homepage for the Deep Impact Mission -- http://deepimpact.umd.edu/stsp/ -- a joint effort between technically-proficient amateur astronomers, professional astronomers with discretionary telescope time, and private observatories to gather valuable ground-based optical data on Comet Tempel 1, the target of the Deep Impact Mission. Provide observations of Tempel 1 to supplement the professional data taken by the mission's science team.ASTEROIDS

METEORITES

Mrs.
E. Hulitt Hodge was struck by a 8.5 pound meteorite
at 1:00 P.M. on November 30, 1954. After it penetrated
the ceiling of her living room and ricocheted off
of the radio, it struck her in the hip while she
slept on the couch. She was seriously bruised,
even though she was covered by two heavy quilts.
This is the only record of a human being struck
by a meteorite. The meteorite is in the permanent
collection at the Smithsonian. [Info from "Rocks From Space," by
O. Richard Norton, Copyright 1994, Mountain Press
Publishing Company, Missoula, Montana]A boy was reported
hit on the head in Mbale, Uganda on August 14, 1992 by a
3 gram meteor fragment that passed through some banana tree
leaves. See http://home.planet.nl/~terkuile/meteorites/mbale/mbale.htmlMeteor near-misses and strikes -- http://astro.wsu.edu/worthey/astro/html/im-meteor/strikes.html